An input device comprises a board 14B whereon a player stands with both feet, and supporting the board such that it can oscillate, and it supplies oscillatory information when the player causes the board to oscillate to the game machine. In the supporting mechanism, the central axis of oscillation is positioned on the lower portion of, or below the board. The center of rotation of swinging movement in the supporting mechanism is positioned below the board 14B. The object is to make the swinging movement of the board, when the player is standing on the board, such as skis, skateboard, or the like, and playing the game, as close as possible to a swinging movement in real life, thereby increasing realism and improving the player's interest in the game.